1. Field of the Invention
The present invention relates generally to damascene semiconductor manufacturing processes, and more particularly, to methods and systems for planarizing features and layers in a semiconductor manufacturing process.
2. Description of the Related Art
In general, the manufacturing of the integrated circuit devices (in the form of semiconductor substrates and wafers) includes the use of plasma etching chambers. The plasma etch chambers are capable of etching selected layers on the substrate as defined by a mask or pattern. The plasma etch chambers are configured to receive processing gases (i.e., etch chemistries) while a radio frequency (RF) power is applied to one or more electrodes of the plasma etch chamber. The pressure inside the plasma etch chamber is also controlled for the particular process. Upon applying the desired RF power to the electrode(s), the process gases in the chamber are activated such that a plasma is created. The plasma is thus configured to perform the desired etching of the selected layers of the semiconductor wafer.
Low volatility byproducts are produced in some prior art plasma etch processes. By way of example, in a copper etch process using chlorine containing gases (e.g., Cl2, HCl, etc), the byproduct is CuClx. CuClx is non-volatile at room temperature. The low-volatility byproducts typically condense on the chamber walls. During each plasma etch cycle, the byproducts build-up on the chamber walls. Eventually the byproducts build-up to a certain thickness. The byproduct build-up then begins to “flake” off of the chamber walls and is therefore becomes a significant particle source. The particles can contaminate the substrates being etched in the chamber.
The copper etchant chemistries are often corrosive to the surface of the remaining copper. This corrosive action can cause uneven pitting and leave an undesirable residue layer that must be removed before subsequent processing can occur. Typically, the substrate is removed from the plasma etch chamber and is cleaned and/or rinsed.
FIG. 1 shows a typical cleaned substrate 100. The substrate 100 has a relatively thick layer of oxide 102 (e.g., copper oxide) on top of the exposed copper device 104. The oxide layer 102 can interfere with subsequent processing (e.g., forming interconnects to the underlying copper device) and therefore must be removed before subsequent processing can be attempted. The substrate 100 can also have a barrier layer 106.
CMP chemistries can cause problems similar to those described above for the etching chemistries. A substrate is typically cleaned and rinsed after a CMP operation. The CMP process itself and/or cleaning and/or the rinsing operation can also cause an oxide layer to form.
In view of the foregoing, what is needed is a system and method of removing the residue layer while substantially eliminating the formation of the oxide layer or any other undesirable terminating layer.